I’m not sure I understand your question. But maybe this will help. The R8 has a Pre IN option, allowing you to install a preamp ahead of the R8 (which is an integrated amp). The only change in the R8 when in Pre IN mode is the volume control is bypassed. The R8 preamp tube is v7&v8 which is a pair of 6SL7GT’s. In the R8 the 6SN7’s (v6&v9) are in the power stage and work as driver/phase inverter tubes.
